How many nanoseconds are there in 1.00 yr ? (it needs to be shown using only 3 significant figures. i came up with 1.89 x 10^9. however it doesn't seem figured it made a simple calculation error. the answer is 3.16x10^16

Amachinist turns the power on to a grinding wheel, at rest, at time t = 0 s. the wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 96 rad/s. the wheel is run at that angular velocity for 40 s and then power is shut off. the wheel slows down uniformly at 1.5 rad/s2 until the wheel stops. in this situation, the time interval of deceleration is closest to: